In pneumatic conveying systems, the particulate material being conveyed is essentially suspended in air which is caused to move through the conveying tubes at a rather high rate of speed. It is likely that in most pneumatic conveying systems, the particulate material being conveyed is not spread uniformly throughout the cross-sectional area of the conveying tube. Oftentimes there tends to be a concentration of the particulate material at a certain side of the tube; and in instances where the particulate material being conveyed comprises a mixture of two or more substances with different characteristics, the substances will not be spread uniformly across the cross-sectional area of the tube, but may be collected together at one side or another in the tube during the pneumatic conveying.
As a result, it is not possible to simply put a probe into the pneumatic conveying tube and extract a sample as has been done in the prior art because the sample is not likely to be truly representative of the material being conveyed in the system.
Particulate materials that are handled in a pneumatic conveying system tend to be somewhat dusty because oftentimes the particles are exceedingly small. Accordingly, sampling devices that have been used previously for sampling large granular materials such as feed grains, seed, etc., are not suitable for use in obtaining samples of the particulate material flowing in a pneumatic conveying system.